Deep X-ray exposure system with multistage for 3D microfabrication

This paper reports a new deep X-ray exposure system to realize 3D microstructures with controllable curved and inclined walls. Based on a compact synchrotron light source, a dedicated X-ray beamline and the exposure device have been constructed. They could work in exposure environments of vacuum or helium gas. The exposure device was mainly made up of 5 stages and had as many as 6 degrees of freedom, which enabled the system to have more functions than the normal one. Besides the scan in its plane, the substrate surface could also rotate round one of its normal and tangent respectively. Driven by a PZT stage, the X-ray mask could move freely in its plan against the substrate behind, which were used to control the wall inclination and flexure of the substrate structure. The system also had off-line mask-substrate alignment function. Various 3D PMMA microstructures can be realized by the system, such as lens array, nozzles, tube connector, conical tubes, inclined channels, long circle channels, angle pipe with smooth joint, cone, gear rack, long column with curve cross-section etc., which are impossible with the normal X-ray lithography system. A series of deep X-ray lithography experiments have been completed and obtained some interesting 3D PMMA microstructures and the relationship between the etching depth and the dose energy of the exposure. It demonstrated the potential of the system, which will greatly enlarge the application fields of deep X-ray lithography and LIGA process.